This invention relates to marking devices, and more particularly to hand stamps of the type having a self-contained ink reservoir. These are often used, for example, in manufacturing processes to indicate that a particular component or assembly has been inspected at a quality control station or the like.
More particularly, the invention relates to a self-inking hand stamp that utilizes both a porous die head and an ink-containing reservoir that cooperate to continuously supply ink to the marking face of the stamp so as to provide an exceptionally high number of marking repetitions.
Prior art self-inking hand stamps currently in use often utilize a die head containing the indicia to be marked, that is formed of an open-celled microporous material capable of being saturated with a supply of liquid ink. A typical material utilized for this purpose is identified by the trade designation SP, and is manufactured and sold by Porelon, Inc., of Cookeville, Tenn. Stamps utilizing these die heads typically are capable of several thousand marking repetitions. However, after the ink supply is depleted. The stamp is generally discarded and replaced with a new device.
While these self-inking stamps are useful and generally satisfactory, the process is wasteful in that the manufacture of the die head (and the forming of the particular indicia to be marked) is generally done on a custom basis. Thus, the die heads are relatively expensive.
Also, prior art self-inking stamps are generally provided with a dedicated handle that may be suitable for some users, but which others may find awkward. For example, some workers or inspectors in manufacturing facilities may desire to place the stamp on the rearward end of a pencil or pen also used in their work.
Some prior art self-inking stamps have utilized a housing on which disposable die heads may be mounted and replaced so that the housing, handle, etc., may be used over and over with different die heads. When this is done, there is usually a retainer formed integrally with the die head that is discarded when the ink supply of the die head is depleted.
Most importantly, it is desirable in the use of stamps to obtain maximum utilization of the stamp (i.e.) a maximum number of marking cycles) in order to avoid frequent replacement and the resulting inconvenience. Self-inking stamps currently used have a limited service life, and this can have a major impact on manufacturing efficiency.
The self-inking stamp of the present invention, however, reduces the difficulties indicated above and affords other features and advantages heretofore not obtainable, including a much greater service life.